the von Neumann entropy of the canonical purification reduced to \(A A^\star \)  where \(A^\star \)  is the reflection of \(A\) . We will review the definition in more detail and recall some basic properties of \(S_R(A:B)\)  in Section . While an operational interpretation of \(S_R(A:B)\)  is lacking, and its broader status as a quantum information measure is not yet clear (see Ref. [1]} for some recent progress), reflected entropy has the advantage that it is computable using various analytic and numerical techniques.
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